The guiding principle for this application is that the management of chronic diseases in the elderly must embrace the considerable heterogeneity of the elderly population and must be based on an understanding of which older patients are most likely to progress to symptomatic disease. Chronic kidney disease (CKD) is a common condition in the elderly and older age is a risk factor both for death and for progression to end-stage renal disease (ESRD) among patients with CKD. However, few data exist to guide management of CKD in the elderly. The central question underlying the proposed research is how CKD should be managed in older patients. The research agenda proposed here will focus on the specific area of pre-dialysis planning in the elderly. Among those who ultimately develop ESRD, early intervention to prepare for dialysis is associated with better outcomes and fewer complications after initiation of dialysis. Therefore, it is currently recommended that patients be referred to a nephrologist for preparation for dialysis when they develop severe CKD or approximately one year before onset of ESRD. Because of poor outcomes associated with CKD and low pre-dialysis nephrology referral rates in elderly patients beginning dialysis, there is growing support for interventions to increase nephrology referral and CKD awareness among primary care providers. However, due in large part to the substantial competing risk of death in the elderly, even patients with severe CKD are much more likely to die than to progress to ESRD. Thus, broad efforts to increase nephrology referral among elderly patients with severe CKD may result in potential harm (e.g. unnecessary vascular access placement and clinic visits) in patients unlikely to require dialysis. To identify ways to improve targeting of nephrology referral to those elderly patients most likely to progress to ESRD we will: 1) examine predictors of short-term onset of ESRD in a national cohort of elderly veterans with severe CKD, 2) identify predictors of "under referral" of elderly patients at highest risk for progression to ESRD in the same cohort, and, 3) recruit a cohort of patients 75 years and older with moderate to severe CKD in order to determine whether: 1) use of cystatin C (a novel measure of renal function), and 2) simple "bedside" assessment of functional status can improve our ability to identify those elderly patients with advanced CKD most likely to survive to ESRD.